B1773

SUPPLEMENTAL RESTRAINT SYSTEM: OCCUPANT CLASSIFICATION SYSTEM: B1773: Belt Tension Sensor Circuit Malfunction

DTC B1773 - Belt Tension Sensor Circuit Malfunction

DTC B1776 - Seat Belt Tension Sensor Power Source Circuit Malfunction

DESCRIPTION

The seat belt tension sensor circuit consists of the occupant classification ECU and the seat belt tension sensor.
The seat belt tension sensor sends the seat belt tension signal to the occupant classification ECU.
DTC B1773 and B1776 are recorded when a malfunction is detected in the seat belt tension sensor circuit.





HINT: When DTC B1650/32 is detected as a result of troubleshooting for the "AIRBAG SYSTEM", check the DTCs stored in the occupant classification ECU. When DTC B1773 and B1776 are output, perform troubleshooting for the DTC.

WIRING DIAGRAM





INSPECTION PROCEDURE
HINT: - If troubleshooting (wire harness inspection) is difficult to perform, remove the passenger seat installation bolts to see the undersurface of the seat cushion.

PROCEDURE

1. CHECK FOR DTC
(a) Turn the ignition switch ON.
(b) Clear the DTCs stored in the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.
(c) Clear the DTCs stored in the center airbag sensor Removal.
(d) Turn the ignition switch OFF.
(e) Turn the ignition switch ON.
(f) Check for the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1773 and B1776 are not output.
HINT: Codes other than B1773 and B1776 may be output at this time, but they are not related to this check.

OK -- USE SIMULATION METHOD TO CHECK
NG -- Continue to next step.
2. CHECK CONNECTION OF CONNECTOR
(a) Turn the ignition switch OFF.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Check that the connectors are properly connected to the occupant classification ECU and the seat belt tension sensor.
OK:
Connectors are properly connected.
NG -- CONNECT CONNECTORS PROPERLY
OK -- Continue to next step.
3. CHECK CONNECTOR
(a) Disconnect the connectors from the occupant classification ECU and the belt tension sensor.
(b) Check that the connectors (on the center airbag sensor side and seat belt tension sensor side) are not damaged.
OK:
Connectors are not deformed or damaged.
HINT: If the connectors are not connected securely, reconnect the connectors and proceed to the next inspection.

NG -- REPAIR OR REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
4. CHECK FRONT SEAT WIRE RH




(a) Connect the negative (-) terminal cable to the battery.
(b) Turn the ignition switch ON.
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:





(d) Turn the ignition switch OFF.
(e) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(f) Using 2 service wires, connect terminals 1 (GBT) and 3 (BT), and connect terminals 1 (GBT) and 2 (VBT) of connector C.
NOTE:
Do not forcibly insert the service wires into the terminals of the connector when connecting the wire.
(g) Measure the resistance according to the value(s) in the table below.
Standard resistance:





(h) Disconnect the service wires from connector C.
(i) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE FRONT SEAT WIRE RH
OK -- Continue to next step.
5. CHECK FOR DTC
(a) Connect the connectors to the occupant classification ECU and the seat belt tension sensor.
(b) Connect the negative (-) terminal cable to the battery.
(c) Turn the ignition switch ON.
(d) Clear the DTCs stored in the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.
(e) Clear the DTCs stored in the center airbag sensor Removal.
(f) Turn the ignition switch OFF.
(g) Turn the ignition switch ON.
(h) Check for the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1773 and B1776 are not output.
HINT: Codes other than B1773 and B1776 may be output at this time, but they are not related to this check.

OK -- USE SIMULATION METHOD TO CHECK
NG -- Continue to next step.
6. REPLACE FRONT SEAT OUTER BELT ASSEMBLY RH (SEAT BELT TENSION SENSOR)
(a) Turn the ignition switch OFF.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Replace the front seat outer belt Removal.
HINT: Perform the inspection using parts from a normal vehicle if possible.
(d) Connect the negative (-) terminal cable to the battery.
(e) Turn the ignition switch ON.
(f) Clear the DTCs stored in the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.
(g) Clear the DTCs stored in the center airbag sensor Removal.
(h) Turn the ignition switch OFF.
(i) Turn the ignition switch ON.
(j) Check for the DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1773 and B1776 are not output.
HINT: Codes other than B1773 and B1776 may be output at this time, but they are not related to this check.

OK -- END
NG -- Continue to next step.
7. REPLACE OCCUPANT CLASSIFICATION ECU
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch ON.
(c) Using the Techstream, save the ECU data from the ECU which has been installed on the vehicle Registration.
(d) Turn the ignition switch OFF.
(e) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(f) Replace the occupant classification ECU Disassembly.
(g) Connect the negative (-) terminal cable to the battery.
(h) Turn the ignition switch ON.
(i) Using the Techstream, load the previous ECU data stored into the new ECU Registration.
(j) Turn the ignition switch OFF.
(k) Turn the ignition switch ON.
(l) Clear the DTCs stored in the memory Reading and Clearing Diagnostic Trouble Codes.
HINT: If DTC is not cleared at this time, past DTC will remain.

NEXT -- Continue to next step.
8. PERFORM SENSITIVITY CHECK
(a) Perform the sensitivity check Initialization.
NEXT -- END